Cerebrospinal fluid circulation: What do we know and how do we know it?

The central nervous system's (CNS) complicated design is a double-edged sword. On the one hand, the complexity is what gives rise to higher order thinking; but on the other hand, damage to the CNS evokes its unforgiving nature. The cerebrospinal fluid (CSF) circulation system is an intricate system embedded in and around the CNS that has been the topic of debate since it was first described in the 18th century. It is underscored by the choroid plexus's distinct vascular network which has conventionally been seen as the most prominent structure in CSF production through a variety of active transporters and channels. Despite the ubiquity of this circulation system in vertebrates, some aspects remain understudied. Recent advances in scientific methodology and experimentation have proven to be effective tools for elucidating the mechanisms of the CSF circulation system and the pathological conditions associated with its malfunction. In this review, we capitulate the classical understanding of CSF physiology as well as a new, emerging theory on CSF production.